The invention relates to infrared radiant burners, and more particularly to an omnidirectional cylindrical radiant burner for use in space heaters.
The type of heater to which this invention relates is disclosed in U.S. Pat. Nos. 3,040,805, 3,129,749, 3,198,240 and 3,310,098. Such a device generally burns a fuel such as propane from a pressurized source mixed with air in a combustion chamber defined by an inner mantle element and an outer grid. The mantle usually comprises a series of overlaid fine wire grids, the coarser outer grid or radiant element being spaced therefrom. Combustion takes place within and adjacent to the fine wire grids of the mantle element. So complete is the combustion that only traces of gases other than carbon dioxide, nitrogen and water vapor are expelled.
Omnidirectional cylindrical radiant heat generators of the type disclosed herein are known and have been employed in various types of heaters such as camping heaters and other small space heaters. Such space heaters are often designed to utilize convection as well as radiation in the transfer of heat from the cylindrical infrared heat generator.
Existing cylindrical infrared burners have had certain shortcomings. The small plenum chamber defined interior of the cylindrical mantle has generally been incapable of adequately mixing air and fuel and sufficiently dispersing the mixture equally through all areas of the mantle. The high velocity of the fuel and air entering the plenum chamber often results in a "flue effect" wherein the mixture tends to flow in a central stream without adequate outward dispersion. The result is that uneven and inefficient combustion occurs with some unburned gases entering the air. Aggravating this problem and also adding to construction costs in the manner in which the mantle grids are usually assembled. Each of the mantle grids generally has some kind of longitudinal seam which may be lapped and welded or interwoven. These seams create areas of resistance and result in cold spots on the otherwise hot glowing mantle.
Another feature of construction in cylindrical burners that may add unnecessary production costs and may result in less efficiency in burning is the manner in which the end caps of the burner are retained together. The fastening means must be simple and relatively unobtrusive to the passage of radiant heat outward from the mantle. Present burner constructions generally fall short of these requirements.